Romano Clementucci

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The Atlas-Meseta intracontinental orographic system of Morocco experienced recent, large-scale surface uplift as documented by elevated late Miocene, shallow-water marine deposits exposed in the Middle Atlas Mountains. The Anti-Atlas Mountains do not present any stratigraphic records that document regional vertical movements, however, the presence of a high-standing, erosional surface, and the transient state of river networks, provides insights into the uplift history of the belt and the mechanisms that drove it. Here, we combine geomorphic and stream profiles analyses, celerity of knickpoints and linear inverse landscape modelling with available geological evidence, to decipher the spatial and temporal variations of surface uplift in the Anti-Atlas and the Siroua Massif. Our results highlight the presence of a transient landscape, and document a long wave-length topographic swell (~ 100 x 600 km) with a maximum surface uplift of ~1500 m in the Siroua Massif and ~1100 m in the central Anti-Atlas starting from ~10 Ma, in association with late Miocene magmatism in the Siroua and Saghro Massif and contractional deformation in the High Atlas. Uplift rates for the central Anti-Atlas range between 70 and 180 m/Myr, fall within the same order of the rates obtained from uplifted marine deposits suggesting a similar deep-seated mechanism of uplift most likely related to astenopsheric upwelling. Overall, our approach allows to quantitatively constrain the transient state of the landscape and the contribution of regional surface uplift on mountain building processes.